Automatic transmission



NOV. 28, 1933- .y K wEllHMANN l1,937,002

AUTOMATIC TRANSMI S S ION Filed April 10, 1953 2 Sheets-Shea?l lATTORNEY.

Nov.v2'8, 1933. K. wElHMANN `AUTOMATIC TRANSMISSION 2 Sheets-Sheet 2Filed. April l0, 1933 INVENTOR.

T mm wf/f/M/W/V. BY C/*794mg MM ATTORNEY.

several gures thereof.

Patented Nov. 28., 1933 `UNITED STATES `Iaaraii'r OFFICE 1,907,002 lAUTOMATIC TRANSMISSION Kai-1 Weinmann, Detroit, Mien. I ApplicationApi-i1 10,1933. serial No. '665,313

11 (ci. 'I4-'34) I f This invention relates to power transmissionswherein it is necessary to provide for changes in gear ratio between thepower source and its pointof application. A most common instance of theuse of such mechanism is in the modern automobile.

An adaptation of my invention to anY automobile transmission .isdescribed herein. It comprises Ameans whereby a change in gear ratio canbe effected automatically andfwithout necessity of mechanical shiftingand consequent clashing of the gears. v

While my invention is particularly adapted to the automotive eld, itwill no doubt prove equally adaptable to other arts, as will be evidenttov persons skilled in the arts concerned.

Because of the novel features of myinvention it is possible to attainextreme simplicity of design while retaining all the necessary functionsand refinements so much desired.

With the foregoing and certain other objects and characteristics inView, which will readily be recognized from the following description,the invention' consists in certain novel features in construction, andin combination and arrangements of elements as will be more fully andparticularly referred to and specied hereinafter.

Referring to the accompanying drawings, in which similar referencecharacters refer to corresponding parts or elements throughout the 1shows a crosssection of my transmission showing in entirety the novelcombination of mechanical elements which comprises myA invention;

Fig. 2 is a section'taken substantially on the line 2-2 of Fig. 1 andshowing also a view of gearing directly forward of section 2-2;

Fig. 3 is a section taken substantially on@ the line 3 3 of Fig. 1 andshowing also a view of gearing directly forward of section 3--3;

Fig. 4 is a perspective view, more or, less diagrammatic, of a controlhook-up for my transmission.

' An important unit of my transmission is a differential gear unitinterposed between sections of the main drive shaft. The shaft 10 fromthe source of power is provided with bevel gear 11 meshing with bevelgears 12 rotatable on spider arms 13a. Gears 12 mesh also with bevelgear 14 which connects with shaft 15. The shafts 10 Yand 15 arerotatably mounted in housing 16 of the differential unit, four bearings17 being provided. Two bearings 18 and 19 are also provided` for supportofthe ends of shafts 10 and 15 vin the spider 13. Likewise bearings'20are provided on spider arms 13a-for rotation of gears 12.

The spider 13 and gears 12 are carried by housing 16 andv said housingis rotatably mounted on bearings 21 and 22, which are in turnsupportedby the main transmission housing 23. Housing 23 is suitably designed forassembly in several `component parts as shown.

Near the outer periphery and on both sides of the differential housing16, I provide flat surfaces 25 and 26 with annular clutch plates 21 and28 in close proximity thereto. I also provide pressure plate 29 operableby spring units 30 to compress clutch plates 2'7 and 28 againstdifferential housing 16 thereby preventing its rotation. Mechanismholding pressure plate 29 out of contact-With the clutch plates topermit rotation of the differential unit is described inA anotherportidn of Athis speciflcation.

A gear 31 is keyed to the rear extremity of the 75 differential housing16 for rotation therewith.; Thisgear meshes with gear 32 rotatable onshaft 33 (see Fig. 2). The gear 32 meshes with gear 34 which isconnected with gear 35 by sleeve 36, all rotating on countershaft 37,suitable bearings 38 being provided.. The countershaft gear .35 mesheswith gear 39. The gear 39 is mounted for rotation on member 40, beingprovided with bearings 41 and 42. Member 40 is keyed to hollow shaft 43.Said shaft 43 is attached by a conventional splined connection to shaft15. Bearings 44 and 45 are provided for rotatable sus'- when drive isapplied to the teeth of gear 39 in a clockwise direction (as viewed inFig. 2), thev rollers 48 are driven to the narrow end of notches 47 andcause drive to be transmitted -to member 40 and thereby to hollow shaft43. However, if a driving force in clockwise direction is applied tomember 40 the rollers 48 are carried to thel wide end of notches-47 andthe shaft 43 and members 40 are free to rotate without impartingrotation to gear 39. It is evident that this con- 105 struction allowstorque to be .transmitted from f gear 39 to shaft 43 byclockwiserotation of said gear. However,A when torque transmitted toshaft 43 from the shaft 15 predominates, the shaft 43 will rotate freeof gear 39. The opera- /uo ltion of this unit in cooperation with theother umts of my transmission will be made evident 'later in thisspecification.

A gear 49 is secured to shaft 43 by nut 51 which also serves tosecurethe shaft 43 from longitudinal movement. A shaft 52 rotates onbearing 53 inthe end of shaft 43 and on bearing 54 in the end of mainhousing 23. This shaft52 is provided with universal joint yoke-55 whichis secured to shaft 52 by means of nut 56. Gear and dogclutch unit 57 isfree to slide longitudinally on shaft 52 but is splined thereto.Manually operated means (not shown) makes possible movement of the part57 to its forward position, engaging with gear 62. The connectionbetween shafts 43 and 52.is no longer eifectedsince dogs 58 noV longerengage recesses 59 of gear 49. The drive is now from gear 49 to gear 60to gear 6l, to gear 62, to gear 57 and thereby. to shaft 52. Manualwhich can be manually set to close an electrical operation lof part 57may be accomplished by the Y conventional lever which is not shown.

Fig. 4 shows a means for operation of the pressure plate 29 to controlrotation of the differential housing 16. It is remembered that springunits 30 (Fig. 1) act on pressure plate 29 to compress clutch plates 27and 28 against surfaces 25 and 26 thereby preventing rotation ofdifferential hous- -tended unbroken position (as shown) are holdingpressure plate 29 out of operation against resistance of spring units 30through lever 1 08, shaft 109 and levers 110. At 101 is provided amechanism operable in proportion to vehicle speed contact at apreviously selected vehicle speed. This result may be accomplished byseveral means well known in the art and no detailed explanation of unit101 is required herein. 'I'he closing of the circuit at 101 causeselectrornagnet`A 102 to move lever 103 which acts, by contact with lowerend of bolt 104 on link 105, to break joint 107 which connects links 105and 106. As soon as joint 107 .is broken there is no longer anyrestraint on spring units 30 so'they immediately act to bring pressureplate 29 into action, this causing differential housing 16 'tobesecurely held in a stationary position.

A dash-pot unit 111 may be provided to makev the transition less abruptwhen breaking of joint 107 releases suddenly the spring pressure ofunits 30. Shaft 116 (Fig. 4) is connected to the conventional clutchpedal. Depression of the clutch pedal causes shaft 116 torotate'counter-clockwise as viewed inFig. 4.` Such rotation causes lever115 -to exert pressure at 114 and through 'is left free to rotate.

lis generally termed low gear.

tated from the source of power, rotates the gearv The slot 114 allowsoperation of the clutch after the setting of the links and 106 isaccomplished. i

The operation of my transmission is as follows:

In general the mechanism provides for low gear" operation when thedifferential housing 16 plate 27. All intermediate gear ratiosfaeautomatically accomplished in this transmission and the provision fora shift to lintermediate -is unnecessary. When the car is accelerated toa desired speed it isrno longer necessary to allow the housing 16 torotate and it is therefore stopped entirely and held stationary bypressure plate 29 actuated by spring units 30 as previously described.This cutting out of automatic gearratio control is arbitrary with thedriver or h e may set the unit 101 (Fig. 4) to accomplish it auto- Ashas been previously de- `vscribed accomplished by mechanism holdingpressure ring 29 out of contact with clutch vot matically at any speeddesired. With the differential housing 16 stationary the gear ratiois 1to 1, the drive going through gears 11, 12 and 1.4vas

a stationary gearv train. l 1,

In starting a car equipped with my transmission, the clutch pedalisfiirst depressed in the conventional manner. A manuallyoperated le- Iver is used to slide dog clutch unit 57 to its most 'forward positionthereby connecting` shafts 43 11 which causes the epicyclie unit,comprised of spider 13, gears 12 and housing 16 to rotate in the samedirection as the shaft 10. This rotation of the spider .13, gears 12 andhousing 16 is accomplished because of difference in the rate ofkrotation of gears 11 and 14. If gear 14 were stationary the housing 16would turn at one-half the vrate of shaft 10. However this is not thecase as rotation of housing 16 and its attached gear 31 causes the geartrain 32, 34, 35 and 39 topperate. The reversal caused by interposingidler 32 causes gear 39 to impart rotation to member 40 and shaft 43 ina direction opposite to that of housing 16 and shaft 10. Shaft43 isconnected housing 16. Thus the gear ratio of the countershaftgear train(32, 34, 35 and 39) reflects itself Shaft 10, ro-

'to the shaft 15 and shaft 15 rotates gear 14 in a Adirection alsoopposite to that of shaft liand back on Ithe gear 14 and causes housingv16 with i spider 13 and gear 12 to turn at a-slower rate than would bethe. case if gear 14 were stationary. This slowing up of theprocessional movement of the spider 13 tends to allow some drive by thegear 1-1 directly through gears 12, tending to rotate gear 14. The shaft15 may therefore rotate faster than the gear 39 because of the slipallowed by the overriding or free-wheeling clutch unit 40. Themechanical advantage (or effective gear ratio) will be decreased as thecar y accelerates because of the properties of the overriding clutch.The tendency is to slow up housing 16 as the load on the driven shaftbecomesv less and an effective gear ratio nearer unity will be attained.To better understand this, assume the car on a level pavement startingfrom a full stop. When the clutch is thrown in the meopposite to thedirection of. rotation of said epito turn, the gear 14 and the maindrive shaft are rotated through the counter shaft gear train 32, 34, 35and 39, this increases in rotation of gear 14 and slows up the housing16, which allowsv partial drive through gears 12 and shafts 15 and 43rotate faster than gear 39 and overriding clutch 40 slips to allow thischange. By the properties of the differential hook-up the inechanicaladvantage is reduced when difference in rate of rotation of gears 11 and14 becomes less. As the car picks up to a constant speed on level roadthere is a tendency for the load o n the driven shaft to decrease. Thistendency to coast allows the overriding clutch to slip still more andthe housingl 16 rotation is still further slowed producing still furtherreduction in gear ratio. 'Ihe gear ratio assumed is appropriate to theload imposed. Assuming that a steep grade is encountered the rotation ofshaft 43 will immediately begin to lag. This causes the housing 16 toimmediately rotate relatively faster and take up the drive of the shaft43 through the counter-shaft gear train. A greater mechanical advantageis also effected automatically by the properties of the differentialhook-up. It is evi-` dent that the overriding clutch unit 40 acts as aselector moving the gear ratio toward one end or the other of theavailable range according as load is increasing or decreasing.Mechanicaladvantage appropriate to conditions is therefore maintainedwithout necessity for intermediate mechanical shifts.

As stated before a straight 1 to 1 ratio is available to the driver atany speed he desires it by `mechanism holding the housing 16 stationary,

scope of my invention, and hence I do not desire' to limit myself to theexact and specic disclosure hereof.

Desiring to protect my invention in the broadest manner legallypossible, what I claim and desire to secure by Letters Patent of theUnited States is:

I claim:

' 1. In a transmission, the combination, a driving shaft, a drivenshaft, oppositely disposed gears secured one to each of said shafts, anepicyclic gear unit rotatable by differential action between saidoppositely disposed gears, a gear train connecting said epicyclic unitwith said driven shaft, and a torque` operated clutch unit in said geartrain.

2. In a transmission, the combination, a driving shaft, a driven shaft,oppositely disposed gears secured ontol each of said shafts, anepicyclic gear unit rotatable by differential action between saidoppositely disposed gears, a gear train lconnecting said epicyclic unitwith said driven shaft, one gear of said train provided with a clutchcausing disengagement of said train when rate of rotation of said drivenshaft tends to exceed rate of rotation imparted by said train.

3. In a transmission the combination, a driving shaft, a driven shaft,oppositely disposed gears secured one to each of said shafts, anepicyclic gear unit rotatable by differential action between saidoppositely disposed gears, a gear train connectingsaid epicyclic gearunit with said driven shaft, an idler in said gear train causingrotation of said driven shaft in a direction cyclic gear unit.

4. In a transmission, the vcombination, a drlv'- ing shaft, a drivenshaft, V oppositely disposed gears secured one to each of said shafts,an epicyclic gear unit rotatable by differential action between saidoppositely disposed gears, a gear train connecting said epicyclic gearunit with said driven shaft,`an idler in said gear train causingrotation of said driven shaft in a direction opposite to the directionof rotation of said epicyclic gear unit, one gear of said train provided'rotatable within said housing and connectedwith said driving shaft, asecondary differential gear also rotatable within said housing andconnected with said driven shaft, the epicyclic unit of saiddifferential gear train connected with said housing and rotatabletherewith, a countershaft gear train connecting said housing with saiddriven shaft,` a clutch in said countershaft gear train providingdisengagement of said train when rate of rotation of said driven shafttends to exceed rate of rotation imparted by said train.

6. In a mechanism providing for change of gear ratio, the combination, arotatable housing, a differential gear train enclosed in said housing,said differential gear train interposed between a driving and drivenshaft, an element ofsaid differential gear train connected with saidhousing and rotatable by differential action of said driving and drivenshafts, a countershaft gear train connecting said housing with saiddriven i shaft, means preventing rotation of said housing and saidcountershaft gear train thereby providing high gear operation, meansallowing rotation of said housingand said countershaft gear h trainthereby providing low gear operation.

7. In a power transmission mechanism, a means providing a variablemechanical advantage comprising, a'driving shaft, a driven shaft, a unitrotatable by difference in rotation of said driving shaft and saiddriven shaft, a secondary connecting means providing mechanicaladvantage between said rotatable unit and said driven shaft,

a torque operated clutch in said secondary connecting means incooperative action with said rotatable unit and said drivenshaftproducing a variation in mechanical advantage substantially `inproportion to the load on said driven shaft.

a clutch between said secondary means and said driven shaft, said clutchso constructed as to disengage when rate of rotation of said drivenshaft tends to exceed rate of rotation imparted by said secondary means,said secondary means 'in cooperative action with said rotatable umt'saidclutch and said driven shaft producing a variation inmechanicaladvantage substantially in proportion to the load on said driven shaft.

9. In a power transmission mechanism, a means providing variablemechanical advantage comprising, a sectional shaft, a unit rotatabiebydii'- ference in rotation of two sections of said shaft,

-trip mechanism.

a secondary means providing mechanical advantage between said rotatableunit and one oi!v said shaft sections, a clutch connection interposed insaid secondary means, said clutch provided with means to disengage whenrate of rotation of saidy shaft section tends to exceed rate of rotationimparted by'said secondary means. 10. Inapower transmission mechanism,adrive shaft, an epicyclic unit rotated by differential action betweensections (of said shaft, secondary rotating means connecting saidepicyclic unit with one of said shaft sections, a contacting membermovable to prevent rotation of said epicyclic unit,;

pressure means, a trip mechanism to release said contacting member',means for control of said 12. In an automatic transmission, a vsectionaldrive shaft,a differential .gear train interposed between sections ofsaid drive shaft, a secondary gear trainconnecting a unit of saiddifferential gear train with a section of said drive shaft, a

torque operated clutch'in said secondarygear train.

13. In an automatic transmission, a sectior'ial 1,93%;002 l Y i 'fdr'ive shaft, adifferential gear train interposed betweensections ofsaid drivel shaft, a secondary gear train connecting a unit of saiddifferential gear train with a section of said drive shaft, and a freewheeling clutch connection in said secondary gear train. f

14. In a transmission, a driving shaft, a driven shaft, a differentialgear train interposed between said driving and said -driven shaft, asecondarygear train rotated by a unit of said differential gear train, atorque responsive clutch automatically operable to connect saidsecondary gear train with said driven shaft.

15. In a transmission, a driving shaft, a driven shaft, an epicyclicunit rotatable by differential action between said driving shaft andsaid driven shaft, a secondary gear train rotated by said epicyclicunit, a torque aoperated clutch effecting a driving connection betweensaid secondary gear train and said driven shaft.

16. In a transmission, a driving shaft, a driven shaft, an epicyclicunit rotatable by differential action between said driving shaft andsaid driven shaft, a secondary gear train rotated by said epicyclicunit, a clutch operated by the torque transmitted in said secondary-geartrain and effecting a selective driving connection between v saidsecondary gear train and said driven shaft.

1'?. In a power transmission mechanism providing for automatic change ofmechanical advantage, a. driving shaft, a driven shaft, an epicyclicunit rotatable by differential action of said driving shaft and saiddriven shaft, a contacting Y member movable -to prevent rotation of saidepicyclic -unit, secondary means connecting said 110.

epicyclic unitto said driven shaft a torque op. erated clutch in saidsecondary connecting means.

